The past decade has been marked by the convergence of computer and electronic entertainment technologies. The continually decreasing cost of “computer power” has led to very extensive aesthetic advances in the electronic entertainment technologies at little or no additional cost to the consumer. Audio systems for the playing of music have reaped the benefit of these technical advances. Audio systems of higher and higher quality and sophistication are being marketed and installed in automobiles. Of course, with the benefit of quality, there are attendant detriments. There is a clear tenancy on the part of audio system users to listen to music at volumes that not only distract a driver's attention from the road to the music, but is so loud that it covers or masks sounds like the sirens of emergency vehicles that a driver must be alert to.
This is particularly true in the case of young people listening to music in the broad category of rock music. In addition, within the closed confines of an automobile, the loudness is reinforced by the reverberations within the body housing. Of course, in the case of listeners of music such as rock music, there is the continuing effect of loud music above 85-90 decibels doing long term damage to the hearing of the listeners.
Among existing methods addressing these problems are systems that just filter out the audio system music volumes that would produce loudness above, for example, 80 decibels. This may unduly limit the quality of the music since even relatively low decibel played music may occasionally go above such levels for short periods for accent purposes.
Other proposed solutions involve the recognition that relative loudness increases with increases in frequency so that, for example, music having a frequency of 2500 Hz will be louder than music of the same amplitude but having a lower frequency of 2000 Hz.